It has been considered desirable for many years to be able to effectively remove pollutants from the ambient atmosphere in such a way that they will not re-enter the environment, with a minimum of energy input. This came more to the forefront in early 2007 by the issuance of a report by the United Nations Intergovernmental Panel on Climate Change which concluded—in such a stark manner that even the few remaining skeptics found hard to ignore—that human activity is warming the Earth at a potentially catastrophic rate, and in a manner that may be irreversible unless immediate steps are taken. Shortly thereafter, the Virgin Earth Challenge was initiated. The Virgin Earth Challenge is a competition seeking techniques and equipment to temper or reverse climate change by removing at least a billion tons a year of carbon dioxide (or carbon dioxide equivalent) from the atmosphere.
In the August, 2005 edition of Popular Science an article by Michael Behar entitled “How Earth-Scale Engineering Can Save the Planet” looks at six massive scale proposals for dealing with global warming due to carbon dioxide emissions. Some of the six proposals suggest ways to remove carbon dioxide from the atmosphere, but all of the proposals are rated in the article as impractical, too risky, or insufficient.
Carbon dioxide sequestration by burial is one of the proposals. Carbon dioxide is liquefied where it is generated, and injected underground. However there could be serious problems with leakage from any underground storage facility, and the proposal does not assist in removing already existing carbon dioxide form the atmosphere.
Another proposal is to seed parts of the ocean in the Southern Hemisphere with iron to increase algae bloom with the hope that dying plant life will sink to the ocean floor and sequester its carbon content at the bottom of the ocean. This proposal has had many recent skeptics who say—based upon small scale tests—that actually little carbon will sink to the ocean floor. Also, even if effective, the proposal has off-the-chart environmental risks, including the possibility of making the ocean more acidic and killing many desirable species.
Perhaps the most practical of the proposals is that initially presented by Dr. Klaus Lackner in 1999 and sometimes referred to as “Synthetic Trees” or “Wind Scrubbers”. Under this proposal, CO2 absorbing material (such as limewater) would be associated with Venetian blind-like slats that are supported by pedestals. As wind blows through the slats, the CO2 in the air is absorbed by CaOH or NaOH, and periodically removed. After removal, the CO2 would be stripped from the absorbing chemical so that the chemical could be reused. Further manifestations of this general concept are shown in Published U S Patent Publications 2006/0051274, 2006/0186562, and 2006/0289003. Major questions that exist with respect to this technology are the practicality and energy efficiency of regenerating the absorbing chemicals after the CO2 absorption, dealing with the removed CO2, and the cost-effectiveness of installing all of the units necessary to have a significant effect on atmospheric CO2 concentration. Also, if not used where there is a clearly prevailing wind, additional energy-intensive and/or expensive equipment must be provided to orient the structure into the wind for maximum efficiency.
One drawback of all of the above proposals is also the fact that they deal with only CO2. While CO2 is the most prevalent greenhouse gas, it is by no means the only one, nor the most damaging per unit volume. Methane (CH4) has about 23 times (per unit volume) the greenhouse effect that CO2 does, and presently contributes at least about 10% of the total greenhouse effect of man-caused emissions.
According to one aspect of the present invention, a method and apparatus are provided which use the general concept of removal of pollutants (including, but not limited to, greenhouse gases such as CO2 and CH4) in disperse form from ambient air in conjunction with already-existing structures, desirably wind turbines. This minimizes the need for structures to be built specifically for pollutant removal, provides the energy necessary to power any aspects of the method or system that require energy, and in general makes better utilization of resources. The apparatus utilized preferably comprises a wind turbine, most desirably a vertical axis wind turbine (VAWT) which makes the direction of the wind irrelevant. While a wide variety of wind turbines could conceivably be used, by far the most practical is a Savonius, such as a classic Savonius, or the type shown in published U S Applications 2006/0153682 or 2007/0212225, or in co-pending utility application Ser. No. 10/854,280 filed May 27, 2004, Ser. No. 11/265,278 filed Nov. 3, 2005, and Ser. No. 11/703,635 filed Feb. 8, 2007 (the disclosures of all of which are hereby incorporated by reference herein).
According to another aspect of the invention, there is provided the general concept of using a fabric substrate for pollution removing materials. While the fabric is desirably used with a wind turbine, that is not a requirement, and the fabric may be used with other equipment as long as it is placed in an outdoor natural substantially ambient air flow path.
Any suitable material may be used which will absorb, react with, and/or otherwise remove carbon dioxide or other pollutants from substantially ambient air (that is at the temperature, humidity, and pressure conditions typically encountered in the atmosphere during normal circumstances). The material may be provided as a wash coat, or attached by tackifier such as an adhesive, to a fabric substrate—or otherwise associated with the fabric. Alternatively, the pollutant-removing material can be sprayed or otherwise applied (in some sort of particle form) to a surface of a vane of a Savonius rotor, either before or after application of adhesive to the surface. After pollutant removal by the removing material, the material may then be washed off the vane surface by applying a high pressure spray which mechanically detaches the material from the surface, and/or by applying a solvent for the adhesive.
According to one aspect of the invention there is provided a wind turbine having a rotating surface. The wind turbine desirably is a VAWT with a substantially vertical surface that includes a pollutant-removing construction or component which removes at least one pollutant from substantially ambient air impacting the surface. A 2-4 vane Savonius wind turbine is preferred.
The VAWT operative surface may include a fabric readily removably covering a main surface of a vane of the VAWT, the fabric having a pollutant-removing material associated therewith. In fact the surface may consist essentially of a fabric having a pollutant-removing material associated therewith (or the fabric may be used in a Dutch four-arm or Portuguese sail windmill).
The pollutant-removing material may be selected from carbon dioxide and/or methane removing materials; and the fabric may be composed of natural and/or synthetic fibers, woven, non-woven, or knit. Providing activated carbon as part of the pollutant-removing material can result in removing both carbon dioxide and methane. That is, a method of removing greenhouse gases may be provided wherein pollutant-removing material including at least some activated carbon, is placed in ambient air flow, and effects substantially simultaneous removal of methane and carbon dioxide.
Alternatively, the pollutant-removing construction or component may comprise a coating or film on the vane surface; or a fabric may have a coating, film, impregnation, integral fiber, or other integral material associated therewith, selected from the group consisting essentially of activated carbon, CaOH, NaOH, magnesium hydroxide, lithium hydroxide, potassium hydroxide, soda lime, magnesium oxide, magnesium hydrooxycarbonate, CaO, calcium carbonate, and combinations thereof. As another embodiment, where a coating or film is provided, the coating or film may be selected from the group consisting essentially of CaOH, NaOH, magnesium hydroxide, lithium hydroxide, potassium hydroxide, soda lime, magnesium oxide, activated carbon particles or fibers, magnesium hydrooxycarbonate, CaO, calcium carbonate, titanium dioxide, and combinations thereof. The coating or film may be held directly on a vane surface by an adhesive.
According to another aspect of the invention, there is provided a method of simultaneously generating electricity and removing at least one pollutant from substantially ambient air by rotating a VAWT in response to ambient wind so that surfaces of the VAWT contact and remove pollutants from the substantially ambient air. The method is preferably practiced so as to remove carbon dioxide and/or methane from substantially ambient air, although other pollutants such as nitrous oxides, carbon monoxide, etc., may be removed. Typically, the VAWT includes vanes having both spill and drive surfaces; and the removal of carbon dioxide and/or methane is accomplished by providing a fabric covering on at least some of the spill surfaces, which fabric has pollutant-removal capabilities. The fabric covering may also be provided on at least some of the drive surfaces. Alternatively, the removal of carbon dioxide and/or methane may be accomplished by providing a coating or film of pollutant removing material on at least some of the spill surfaces
The method may further comprise, at spaced intervals of time, reactivating the pollutant-removal capabilities of the surfaces. Also, the method may further comprise, at spaced intervals of time, removing pollutant-removing fabrics from the VAWT, and installing new fabrics on the surfaces. That is, when the surfaces are fabric or fabric coverings capable of capturing pollutants, the method may further comprise periodically removing the pollutant-containing fabrics from the VAWT and replacing them, and using the removed fabrics as geotextile fabrics, as soil conditioners, or for strip mined area reclamation, or by burning them with other biomass to generate space or process heat or electricity, either as is or after shredding.
According to yet another aspect of the invention, there is provided a method of removing a greenhouse gas pollutant (at least one) from substantially ambient air by placing a fabric, that is associated with material operative to remove the greenhouse gas pollutant, in a natural flow of substantially ambient air in an outdoor environment which receives sunlight. The greenhouse gas removed may comprise at least methane, and the method may further comprise, after the fabric is substantially no longer capable of removing methane, burning the fabric with other biomass to produce space or process heat or electricity, either as is or after shredding. Carbon dioxide may alternatively be removed, or substantially simultaneously with methane. That is, the method may be practiced to effect at least methane removal, or to effect at least substantially simultaneous removal of method and carbon dioxide. The fabric is preferably placed in a natural flow of substantially ambient air by providing the fabric as part of a VAWT, although other structures—including those specifically constructed for that purpose—may be utilized. The flowing ambient air can either pass through the fabric, or only partially pass through it, or only substantially impact the fabric with little or no air passing through.
It is a primary object of the present invention to provide a novel manner of removing pollutants, including greenhouse gases, from the environment while at the same time typically performing another function. This and other objects of the invention will become clear from the detailed description of the invention, and from the appended claims.